The present invention relates to a bar code reading apparatus for reading a bar code used for a sale management (POS: Point of Sale) system in a supermarket or the like.
As a conventional bar code reading apparatus (FIG. 8) for the POS system, one comprising a light source 50, a deflector 53, a pattern forming and light-receiving optical system 54, a photoelectric transducer 56, a video amplifier 57, and a decoder 58, as shown in FIG. 8. Or, as shown in FIG. 9, a reading apparatus may include a light beam output from a single laser oscillator 70 which is split into two beam components by a half mirror 71, a high-density scanning pattern 81 is formed by a deflector 75 and a scanning pattern forming optical system 79. A necessary digitized video signal is obtained by a light-receiving unit having photoelectric transducers 82 and 85, video amplifiers 83 and 86, and signal pre-processors 84 and 87, as shown in FIG. 9.
The conventional bar code reading apparatuses described above respectively have problems. More specifically, although the reading apparatus shown in FIG. 8 has a simple arrangement, since a scanning pattern is simple, a region where a reading rate is degraded is inevitably generated in view of reading performance. On the other hand, although the reading apparatus shown in FIG. 9 can eliminate the problem of FIG. 8 and can improve reading performance, since it has two scanning/light-receiving systems, cost is increased. In addition, since the number of components is increased, reliability is inevitably degraded. Recently, a sedentary operation is under an obligation in Northern European countries. Thus, a demand has arisen for a low-profile bar code reading apparatus to drastically improve operability. The above two bar code reading apparatuses pose a problem in this respect.